chapter 1 introduction 1 chapter 1: introduction
TRANSCRIPT
Chapter 1 Introduction 1
Chapter 1: Introduction
2
Organization Lectures Homework
o Several homeworks with a few correction sessions Quiz
o Several quizzes Mid-term exam Final Exam Grading
3
Exams and Grading Mid-term: 35% Final exam: 40% Homeworkes : 20% Quizzes (bonus): 10%
Note: The number of quizzes vastly exceeds the required minimum. There is no replacement for the quizzes.
Chapter 1 Introduction 4
The Cast of Characters
Alice and Bob are the good guys
Trudy is the bad “guy”
Trudy is our generic “intruder”
Chapter 1 Introduction 5
Alice’s Online Bank Alice opens Alice’s Online Bank
(AOB) What are Alice’s security concerns? If Bob is a customer of AOB, what
are his security concerns? How are Alice’s and Bob’s concerns
similar? How are they different? How does Trudy view the situation?
Chapter 1 Introduction 6
CIA CIA == Confidentiality, Integrity,
and Availability AOB must prevent Trudy from
learning Bob’s account balance Confidentiality: prevent
unauthorized reading of information o Cryptography used for confidentiality
Chapter 1 Introduction 7
CIA Trudy must not be able to change
Bob’s account balance Bob must not be able to improperly
change his own account balance Integrity: detect unauthorized
writing of informationo Cryptography used for integrity
Chapter 1 Introduction 8
CIA AOB’s information must be available
whenever it’s needed Alice must be able to make transaction
o If not, she’ll take her business elsewhere
Availability: Data is available in a timely manner when needed
Availability is a “new” security concerno Denial of service (DoS) attacks
Chapter 1 Introduction 9
Beyond CIA: Crypto How does Bob’s computer know
that “Bob” is really Bob and not Trudy?
Bob’s password must be verifiedo This requires some clever
cryptography
What are security concerns of pwds?
Are there alternatives to passwords?
Chapter 1 Introduction 10
Beyond CIA: Protocols When Bob logs into AOB, how does AOB
know that “Bob” is really Bob? As before, Bob’s password is verified Unlike the previous case, network
security issues arise How do we secure network
transactions?o Protocols are critically importanto Crypto plays critical role in protocols
Chapter 1 Introduction 11
Beyond CIA: Access Control
Once Bob is authenticated by AOB, then AOB must restrict actions of Bob
o Bob can’t view Charlie’s account info
o Bob can’t install new software, etc.
Enforcing these restrictions: authorization
Access control includes both authentication and authorization
Chapter 1 Introduction 12
Beyond CIA: Software Cryptography, protocols, and access
control are implemented in software What are security issues of software?
o Real world software is complex and buggyo Software flaws lead to security flawso How does Trudy attack software?o How to reduce flaws in software
development?o And what about malware?
Chapter 1 Introduction 13
Your Textbook The text consists of four major
partso Cryptographyo Access controlo Protocolso Software
Note: Our focus is on technical issues
The People Problem People often break security
o Both intentionally and unintentionallyo Here, we consider the unintentional
For example, suppose you want to buy something onlineo To make it concrete, suppose you
want to buy Information Security: Principles and Practice, 2nd edition from amazon.com
Chapter 1 Introduction 14
The People Problem To buy from amazon.com…
o Your Web browser uses SSL protocolo SSL relies on cryptographyo Access control issues ariseo All security mechanisms are in
software Suppose all of this security stuff
works perfectlyo Then you would be safe, right?
Chapter 1 Introduction 15
The People Problem What could go wrong? Trudy tries man-in-the-middle attack
o SSL is secure, so attack doesn’t “work”o But, Web browser issues a warningo What do you, the user, do?
If user ignores warning, attack works!o None of the security mechanisms failed o But user unintentionally broke security Chapter 1 Introduction
16
Chapter 1 Introduction 17
Cryptography “Secret codes” The book covers
o Classic cryptographyo Symmetric cipherso Public key cryptographyo Hash functions++o Advanced cryptanalysis
Chapter 1 Introduction 18
Access Control Authentication
o Passwordso Biometricso Other methods of authentication
Authorizationo Access Control Lists/Capabilitieso Multilevel security (MLS), security modeling,
covert channel, inference controlo Firewalls, intrusion detection (IDS)
Chapter 1 Introduction 19
Protocols “Simple” authentication protocols
o Focus on basics of security protocolso Lots of applied cryptography in
protocols Real-world security protocols
o SSH, SSL, IPSec, Kerberoso Wireless: WEP, GSM
Chapter 1 Introduction 20
Software Security-critical flaws in software
o Buffer overflowo Race conditions, etc.
Malwareo Examples of viruses and wormso Prevention and detectiono Future of malware?
Chapter 1 Introduction 21
Software Software reverse engineering
(SRE)o How hackers “dissect” software
Software and testingo Open source, closed source, other
topics
Chapter 1 Introduction 22
Software Operating systems
o Basic OS security issueso “Trusted OS” requirements
Software is a BIG security topico Lots of material to covero Lots of security problems to considero But not nearly enough time available…
Chapter 1 Introduction 23
Think Like Trudy In the past, no respectable sources
talked about “hacking” in detailo After all, such info might help Trudy
Recently, this has changedo Lots of books on network hacking, evil
software, how to hack software, etc.
o Classes teach virus writing, SRE, etc.
Chapter 1 Introduction 24
Think Like Trudy Good guys must think like bad
guys! A police detective…
o …must study and understand criminals
In information securityo We want to understand Trudy’s
methodso Might think about Trudy’s motiveso We’ll often pretend to be Trudy
Chapter 1 Introduction 25
Think Like Trudy We must try to think like Trudy We must study Trudy’s methods We can admire Trudy’s cleverness Often, we can’t help but laugh at
Alice’s and/or Bob’s stupidity But, we cannot act like Trudy
o Except in this class…
Chapter 1 Introduction 26
In This Course… Think like the bad guy Always look for weaknesses
o Find the weak link before Trudy does It’s OK to break the rules
o What rules? Think like Trudy But don’t do anything illegal!